Browsing by Author "Hashem Y.A."

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Biofilm formation in enterococci: Genotype-phenotype correlations and inhibition by vancomycin
(Nature Publishing Group, 2017) Hashem Y.A.; Amin H.M.; Essam T.M.; Yassin A.S.; Aziz R.K.; Department of Microbiology and Immunology; Faculty of Pharmacy; British University in Egypt (BUE); Shorouk City; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; October University for Modern Sciences and Arts; 6 October City; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; Cairo University; Cairo; Egypt
Enterococci are nosocomial pathogens that can form biofilms, which contribute to their virulence and antibiotic resistance. Although many genes involved in biofilm formation have been defined, their distribution among enterococci has not been comprehensively studied on a genome scale, and their diagnostic ability to predict biofilm phenotypes is not fully established. Here, we assessed the biofilm-forming ability of 90 enterococcal clinical isolates. Major patterns of virulence gene distribution in enterococcal genomes were identified, and the differentiating virulence genes were screened by polymerase chain reaction (PCR) in 31 of the clinical isolates. We found that detection of gelE in Enterococcus faecalis is not sufficient to predict gelatinase activity unless fsrAB, or fsrB alone, is PCR-positive (P = 0.0026 and 0.0012, respectively). We also found that agg is significantly enriched in isolates with medium and strong biofilm formation ability (P = 0.0026). Additionally, vancomycin, applied at sub minimal inhibitory concentrations, inhibited biofilm in four out of five strong biofilm-forming isolates. In conclusion, we suggest using agg and fsrB genes, together with the previously established gelE, for better prediction of biofilm strength and gelatinase activity, respectively. Future studies should explore the mechanism of biofilm inhibition by vancomycin and its possible use for antivirulence therapy. � 2017 The Author(s).
Molecular characterization of Enterococcus spp. clinical isolates from Cairo, Egypt
(Medknow Publications, 2015) Hashem Y.A.; Yassin A.S.; Amin M.A.; Department of Microbiology and Immunology; Faculty of Pharmacy; Modern Sciences and Arts University; Giza; Egypt; Cairo University; Cairo; Egypt
Purpose: Enterococci are responsible for serious diseases such as bacteraemia, endocarditis and urinary tract infections. The ability of enterococci to cause such diseases is due to acquisition of certain virulence factors such as haemolysin, gelatinase and enterococcus surface protein. This study has been conducted to investigate the occurrence of virulence factors and resistance to various antibiotics with emphasis on vancomycin in the Enterococcus spp. Materials and Methods: Clinical specimens were collected and isolates were identified by proper microscopic, culture and biochemical tests. Susceptibility and degree of resistance of the isolates to various antibiotics were determined. Virulence factors were examined by phenotypic tests followed by molecular methods. Bioinformatics analysis was used to detect regions in the genomes that might have originated from horizontal gene transfer. Result: The presence or absence of virulence genes did not affect the pattern of antimicrobial resistance in Enterococcus isolates; consequently, no relationship was found between virulence factors and resistance to different antibiotics used. Bioinformatics analysis showed that the virulence genes were mainly transferred by transposons. Conclusion: Among the enterococci, environmental factors may interfere in the expression of virulence factors. Horizontal gene transfer plays an important role in the spread of resistance and virulence genes.